Re: [PATCH v4 18/20] x86: Convert to GENERIC_CMDLINE

Rob Herring
2021-04-08T19:41:48Z

On Fri, Apr 02, 2021 at 03:18:20PM +0000, Christophe Leroy wrote:
> This converts the architecture to GENERIC_CMDLINE.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> arch/x86/Kconfig | 45 ++---------------------------------------
> arch/x86/kernel/setup.c | 17 ++--------------
> 2 files changed, 4 insertions(+), 58 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index a20684d56b4b..66b384228ca3 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -104,6 +104,7 @@ config X86
> select ARCH_USE_QUEUED_SPINLOCKS
> select ARCH_USE_SYM_ANNOTATIONS
> select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
> + select ARCH_WANT_CMDLINE_PREPEND_BY_DEFAULT

Seems to be non-existent kconfig option.

> select ARCH_WANT_DEFAULT_BPF_JIT if X86_64
> select ARCH_WANTS_DYNAMIC_TASK_STRUCT
> select ARCH_WANT_HUGE_PMD_SHARE
> @@ -118,6 +119,7 @@ config X86
> select EDAC_SUPPORT
> select GENERIC_CLOCKEVENTS_BROADCAST if X86_64 || (X86_32 && X86_LOCAL_APIC)
> select GENERIC_CLOCKEVENTS_MIN_ADJUST
> + select GENERIC_CMDLINE
> select GENERIC_CMOS_UPDATE
> select GENERIC_CPU_AUTOPROBE
> select GENERIC_CPU_VULNERABILITIES
> @@ -2358,49 +2360,6 @@ choice
>
> endchoice
>
> -config CMDLINE_BOOL
> - bool "Built-in kernel command line"
> - help
> - Allow for specifying boot arguments to the kernel at
> - build time. On some systems (e.g. embedded ones), it is
> - necessary or convenient to provide some or all of the
> - kernel boot arguments with the kernel itself (that is,
> - to not rely on the boot loader to provide them.)
> -
> - To compile command line arguments into the kernel,
> - set this option to 'Y', then fill in the
> - boot arguments in CONFIG_CMDLINE.
> -
> - Systems with fully functional boot loaders (i.e. non-embedded)
> - should leave this option set to 'N'.
> -
> -config CMDLINE
> - string "Built-in kernel command string"
> - depends on CMDLINE_BOOL
> - default ""
> - help
> - Enter arguments here that should be compiled into the kernel
> - image and used at boot time. If the boot loader provides a
> - command line at boot time, it is appended to this string to
> - form the full kernel command line, when the system boots.
> -
> - However, you can use the CONFIG_CMDLINE_FORCE option to
> - change this behavior.
> -
> - In most cases, the command line (whether built-in or provided
> - by the boot loader) should specify the device for the root
> - file system.
> -
> -config CMDLINE_FORCE
> - bool "Built-in command line overrides boot loader arguments"
> - depends on CMDLINE_BOOL && CMDLINE != ""
> - help
> - Set this option to 'Y' to have the kernel ignore the boot loader
> - command line, and use ONLY the built-in command line.
> -
> - This is used to work around broken boot loaders. This should
> - be set to 'N' under normal conditions.
> -
> config MODIFY_LDT_SYSCALL
> bool "Enable the LDT (local descriptor table)" if EXPERT
> default y
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 6f2de58eeb54..3f274b02e51c 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -5,6 +5,7 @@
> * This file contains the setup_arch() code, which handles the architecture-dependent
> * parts of early kernel initialization.
> */
> +#include <linux/cmdline.h>
> #include <linux/console.h>
> #include <linux/crash_dump.h>
> #include <linux/dma-map-ops.h>
> @@ -161,9 +162,6 @@ unsigned long saved_video_mode;
> #define RAMDISK_LOAD_FLAG 0x4000
>
> static char __initdata command_line[COMMAND_LINE_SIZE];
> -#ifdef CONFIG_CMDLINE_BOOL
> -static char __initdata builtin_cmdline[COMMAND_LINE_SIZE] = CONFIG_CMDLINE;
> -#endif
>
> #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
> struct edd edd;
> @@ -883,18 +881,7 @@ void __init setup_arch(char **cmdline_p)
> bss_resource.start = __pa_symbol(__bss_start);
> bss_resource.end = __pa_symbol(__bss_stop)-1;
>
> -#ifdef CONFIG_CMDLINE_BOOL
> -#ifdef CONFIG_CMDLINE_FORCE
> - strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
> -#else
> - if (builtin_cmdline[0]) {
> - /* append boot loader cmdline to builtin */
> - strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
> - strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
> - strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
> - }
> -#endif
> -#endif
> + cmdline_build(boot_command_line, boot_command_line);
>
> strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
> *cmdline_p = command_line;

Once this is all done, I wonder if we can get rid of the strlcpy and
perhaps also cmdline_p.

Rob